Higher Strength, Mullite-Based Iron Foundry Filter

Abstract

A ceramic foam filter and method of making the filter is described. The filter comprises: a sintered reaction product of: 35-75 wt % aluminosilicate; 10-30 wt % colloidal silica; 0-2 wt % bentonite; and 0-35 wt % fused silica; wherein the ceramic foam filter has less than 0.15 wt % alkali metals measured as the oxide and a flexural strength of at least 60 psi measured at 4 minutes at 1428° C.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to pending U.S. Provisional Patent Appl. No. 61 / 676,500 filed Jul. 27, 2012 which is incorporated herein by reference.BACKGROUND[0002]The present invention is related to improved filters for molten iron and the method of making improved filters for molten iron. More specifically, the present invention is related to improved filters comprising lower alkali content which mitigates the problems caused by the formation of a previously unrealized transient liquid phase that occurs during iron filtration. Much of this liquid phase then ultimately transforms to a previously unrealized solid cristobalite phase during iron filtration.[0003]The filtration of molten iron has been practiced for some time and is well known. Iron filtration has historically been done by passing molten iron through strainers whereby some level of filtration was achieved. More advanced filtration has been done using porous foam mullite ba...

AI Technical Summary

Benefits of technology

The invention is about a new type of porous filter made from mullite. The goal is to make the filter stronger and less likely to fail than previous versions. Another goal is to create a filter that allows for higher flow rates while maintaining strength.

Problems solved by technology

A perplexing problem with porous foam mullite based filters has been the filter rupture, or creep, whereby the filter would either break or deform when subjected to very difficult filtration conditions.

Those of skill in the art long considered the failure to be a mechanical failure due to the rapid change in temperature, coupled with the excessive pressure associated with a large volume of molten iron above the filter.